Strain relief



Jan. 28, 1969 H. J. DELL ET Al. 3,424,416

STRAIN RELIEF Filed Feb. 2l, 1967 United States Patent O 7 ClaimsABSTRACT OF THE DISCLOSURE A device for surrounding a wire conductor orsimilar rod-like member to prevent strain thereon. The device serves todistribute the stress on the conductor over a relatively large area andfurther to serve as a means for mounting a conductor within a panelaperture and for preventing axial movement of the conductor relative tothe aperture; The device is formed of an elastomeric material andcomprises a body member having an interior surface and an exteriorsurface, the exterior surface being joined at its opposite ends to theinterior surface and being spaced at its intermediate position from theinterior surface.

BACKGROUND OF THE INVENTION Field of the invention Strain relievingmeans for electrical conductors or similar rod-like members.

Description of the prior art Various means are known for providingstrain relief for wire conductors. These known devices, however, areVgenerally limited in that they are designed to accommodate oneconductor size or a relatively small range of con* ductor sizes. This isa considerable drawback since it requires a rather large inventory ofparts to accommodate a broad range of conductor sizes. IFurther theknown devices are generally designed for use with one panel aperturesize and do not permit adjustability of the device to accommodate arange of aperture sizes.

SUMMARY OF THE INVENTION This invention provides a device whichaccommodates a broad range of conductor sizes and provides a strainrelief for such conductors. The device is mountable within a panelaperture and prevents axial movement of the conductor relative to theaperture. The device may be supplied in strip form and may be cut tolength to suit any desired panel aperture size.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of astrain relief device shown in successive stages of production and madein accordance with the teachings of the present invention;

FIGURE 2 is a perspective View showing the device of FIGURE l partiallysurrounding a wire conductor;

FIGURE 3 is a perspective view illustrating the strain relief devicemounted in a panel aperture and surrounding a wire conductor;

^ FIGURE 4 is a sectional view showing the strain relief device prior toinsertion in a panel; and

FIGURE 5 is asectional view showing the device after insertion in apanel.

DESCRIPTION OF THE PREFERRED EMBODIMENT The attainments of the presentinvention will become apparent to those skilled in the art upon areading of the following detailed description when taken in conjunctionwith the drawings in which there is shown and described an illustrativeembodiment of the invention; it is to be ICC understood, however, thatthis embodiment is not intended to be exhaustive nor limiting of theinvention but is given for purpose of illustration in order that othersskilled in the art may fully understand the invention and the principlesthereof and the manner of applying it in practical use so that they maymodify it in various forms, each as may be best suited to the conditionsof a particular use.

Turning lirst to FIGURE l there is shown a strip of material 10 whichmay conveniently be supplied in extruded form and made from a suitableelastomeric material. The strip 10` is of indefinite length and issevered to an appropriate length depending on a particular use. When astrain relief is desired for use with a particular aperture in a panel,board, or similar article the circumference of the aperture isdetermined and the end of strip 10 is then severed to a dimension equalto the circumference of the panel aperture. Section 12 shown in FIGURE lrepresents a portion of strip 10 for use with a particular aperturesize.

The section 12 has a generally diamond-shaped crosssectionalconfiguration. A pair of interior surfaces 14 and 16 are provided andhave a plurality of ridges 18 disposed therealong which constitutegripping surfaces as described hereafter. A pair of exterior surfaces 20and 22 are also provided and are joined to the interior surfaces 14 and16 along edges 24 and 26 respectively. Surfaces 20 and 22 are joined bya channel-shaped groove 218 which mates with a panel aperture in amanner to be described.

Section 12 is adapted to be wrapped around an electrical conductor orthe like in a manner as shown in FIGURE 2. Since the conductor diameteris necessarily smaller than the diameter of the aperture through whichthe conductor will extend, the length of the interior surfaces 14 and 16must be less than that of the exterior surfaces 20 and 22. Thecircumference of the electrical conductor to be mounted in the panelaperture is deter mined and this dimension is used to determine the sizeof surfaces 14 and 16. Section 30 is shown in FIGURE 1 and is identicalto section 12 except that the interior surfaces have been severed toappropriate length to accommodate the electrical conductor. The channel28 is the only portion of section 12 which remains at a dimension equalto that of the panel aperture circumference. The strain relief device isshown in FIGURE 4 completely surrounding a conductor 32 and prepared forentry into the aperture 34 located in the panel 36. The conductor 32.,together with the device 30, is then inserted through the panel aperture34 during which insertion the device is caused to be radiallycompressed, such compression being possible due to the space providedbetween the interior and exterior surfaces of the device. When theconductor is sufficiently moved in an axial direction through theaperture 34 the device 30 will snap into place within the aperture andthe channel 28 will be located at the panel to maintain the device inposition. The aperture 34 will exert a pressure on the device 30 in aradially inward direction which will cause the device to rmly grip theconductor by means of the gripping surfaces 18. `In this maner theconductor is prevented from moving in an axial direction and further thedevice 30 serves to prevent rupturing of the conductor due to torsionalstresses.

It can be seen that the strip of material 10 may be selectively severedto provide a strain relieving device capable of use with various sizeconductors and various size panel apertures. It is also apparent that bymaking the device slightly oversize relative to a panel aperture it ispossible to produce increased pressure within the strain relief deviceto thereby provide a firmer `frictional connection between the deviceand the electrical conductor -to thereby further prevent against axialmovement of the conductor relative to the panel.

Changes in construction will occur to those skilled in the art andvarious apparently different modifications and embodiments may be m-adewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only. The actual scope of the invention is intended tobe defined in the following claims when viewed in their properperspective against the prior art.

We claim:

1- A strip of material adapted to be formed into strain relieving means,said strip of material comprising a rst pair of surfaces extendinglongitudinally along said strip, said first pair of surfaces beingjoined to each other along their longitudinal extent and being disposedat an angle to each other, means disposed along the juncture of said rstpair of surfaces for engaging a panel aperture, a second pair ofsurfaces extending longitudinally along said strip, said second pair ofsurfaces being separated from each other and being joined to said rstpair of surfaces, each of said second pair of surfaces being angularlydisposed relative to said rst pair of surfaces and to each other wherebysaid strip is of generally open quadrilateral configuration, andgripping means disposed along said second pair of surfaces for engagingrod-like means ad-apted to extend through said panel aperture.

2. A strip as set forth in claim 1 wherein said first and second pairsof surfaces are formed of an elastomeric material.

3. A strip as set forth in claim 1 wherein said aperture engaging meanscomprises a channel extending longitudinally along said strip.

4. Strain relieving means comprising in combination a panel having anaperture therein, cylindrical means extending through said aperture, andexible means disposed between said cylindrical means and said aperture,said flexible means comprising an interior surface in engagement with said cylindrical means and an exterior surface in engagement with saidaperture, said exterior surface being joined at its opposite ends tosaid interior surface, said surfaces having portions thereof spaced fromeach other and movable toward and away from each other.

5. Strain relieving means as set forth in claim I4 further compnsinggripping means on said interior surface for engaging said cylindricalmeans.

6. Strain relieving means as set forth in claim 4 further comprisingchannel means disposed along said exterior surface for receiving saidaperture.

7. Strain relieving means as set forth in claim 4 wherein said flexiblemeans is split in the directionvof the axis of said cylindrical means.

References Cited UNITED STATES PATENTS 1,204,625 11/ 1916 Wheelock.1,817,774 8/1931 Sipe. 1,967,466 7/1934 Damsel 285-373 X 2,377,5106/1945 Newell 285-373 X 2,3 87,295 10/ 1945 Robertson. 2,417,741 3/ 1947Dillon 285-373 2,420,826 5/ 1947 Irrgang. 2,449,795 9/ 1948 Stillwagon285-373 X 2,451,354 10/1948 Ohls 285-373 X 2,912,712 11/1959 Shamban etal. 3,288,407 11/1966 Downer et al. 248-56 LARAMIE E. ASKIN, PrmmyExaminer.

U.S. Cl. X.R.

